Performance of a novel waste heat-powered ionic liquid-based CO₂ capture and liquefaction system for large-scale shipping

In this work, we proposed a novel CO₂ capture and liquefaction system for large-scale shipping using ionic liquid as capture solvent. By utilizing the waste heat of the exhaust gas and jacket cooling water from the ship's engine as well as the residual pressure energy of the N₂-O₂ mixture from the CO₂ absorption and desorption process, the system's net energy consumption has been significantly reduced. We established the thermodynamic model of the system and investigated the effect of 10 primary system operational parameters on system performance with 3 different ionic liquids as CO₂ capture solvent. The results demonstrated that the system with [DEME][TF₂N] as the CO₂ capture solvent had the best system performance. In addition, we performed a multi-parameter optimization of the system using simulated annealing algorithm with net energy consumption as the optimization objective and the minimal net energy consumption is 0.467 GJ/tCO₂. Compared to the CO₂ capture system that do not utilize waste heat and residual pressure energy, the net energy consumption was reduced by 57.29 % under optimal operational conditions which proves that the novel system significantly reduces the energy consumption of the CO₂ capture and liquefaction process.